Compounds for use as iron (iii) mri contrast agents containing anionic pendents and ancillary groups

A macrocyclic complex comprising:

• a 1,4,7-triazacyclononane (TACN) moiety or an O-substituted TACN moiety;
• one or more anionic pendent groups that are substituents on the TACN moiety or the 0-substituted TACN moiety independently chosen from:
• substituted analogs thereof, deprotonated analogs thereof, stereoisomers thereof, and combinations thereof, wherein R2 is a substituted or unsubstituted alkyl group, a substituted or unsubstituted aromatic group or a substituted ether;
• R3 is a substituted or unsubstituted alkyl or a substituted or unsubstituted aryl group;
• R4 is a substituted alkyl or unsubstituted alkyl or a substituted or unsubstituted aryl group;
• and Q1 is aryl substituted with an anionic group, an alkyl group substituted with an anionic group or an aralkyl group substituted with an anionic group;
• and
• a high-spin Fe(III) cation complexed to the TACN moiety and at least one anionic pendent group substituent of the 1,4,7-triazacyclononane (TACN) moiety or the O-substituted TACN moiety,
• or a salt, a partial salt, a hydrate, a polymorph, or a stereoisomer thereof,
• wherein:
• when the macrocyclic complex has the following structure:
• Z1 and Z2 are
• and Z3 is not
• and/or
• Z1 and Z2 are
• wherein R4 is an unsubstituted aryl, and Z3 is not
• wherein R4 is an unsubstituted aryl.